Hi all I was shooting my .30 impact MK2 today and I was trying out some new ammo so I setup the chronograph and to my surprise it was reading in the range of 680-705 fps!! My normal tune is shooting a similar pellet 880-905 fps… I checked my regulator to see if it had dropped and it was still set to around 140 bar… My hammer spring does feel like it’s smacking a little lighter than I remember but I’m not sure if it’s that or it’s just because it’s shooting 200 fps slower that it would obviously feel like it’s not firing as hard as before..? I’m not a pro tuner but I can usually get it dialed in myself. The only changes I made from the last time I used the chronograph was some minor tweaking of the Valve adjustment closing it a few turns and then opening it back up to right before the 4th line shows… The only thing I can think of is that my spring broke but I don’t think it would even fire if that was the case so I’m stumped.. Has anyone dealt with this issue in the past or if you can tell what my issue is by my description I’d appreciate the feedback. Thank you!
Tuning Impact MK2 lost 200 fps without any adjustments being made
- Thread starter Droppindrakes34
- Start date
If the last thing you did was mess with the valve adjusting screw then you might try to adjust it out again until the velocity is where it was before you messed with it. Unless you measured it with a caliper you probly did not get it in the same exact place. Even with a good caliper measurement there is still some variance.
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Yeah but I actually have the valve open more than I had it when it was shooting around 900 fps and so if anything it should have increased. I don’t think the valve adjustment could affect the fps that much either because I remember it fluctuated maybe 20-30 fps when I was moving full lines on it but 200 fps drop with the valve showing 4 lines and only shooting in the 700 fps range just really makes me think it can’t be the valve unless by closing it and then opening it back up does something to where you have to reset it another way?
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Possibly a C3 o-ring if yours is the old style and not Delrin. Mine lost power once after near 6K shots and then stopped shooting all together. I found that the c1 hammerseat had come unscrewed from the valve rod. Screwed it back on with a small piece of rubber o-ring stuck in the bottom, an Ernest Rowe idea, and some locktight and have not had any problems since. Piece of o-ring was to keep pressure on the hammerseat kind of like a lock washer would.
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I have had my hammer spring adjuster back off a little with every shot I believe. A drop of locktite fixed that
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Bio is right. Probably something to do with the valve rod assembly. Hammer seat, C3 bumper, valve rod, rod to valve pin coupler. Easy check. Remove bottle and degas gun. Remove valve adjuster components. Check that hammer seat is still attached to valve rod and does not protrude much past 6mm from face of trigger block. FX has good schematics online.
https://fxairguns.com/wp-content/uploads/2020/02/impact-MkII-200212.pdf
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Thank you everyone for your replies I went ahead and took my gun apart as I figured it was probably the c3 Delrin issue bio mentioned as well as meathead online. I got to where the c3 o-ring should have been and there was nothing there!! So I rigged a piece of delrin (or something close to it) as i got it from some spare yong heng compressor parts.. It fits snug enough to tap with the threads and I put it back together. I’m going to try shooting it again here shortly and I’ll report back with my findings thanks again for all the great info and fingers crossed I hope it is shooting like it was before !
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It worked!!! Thank you Bio for bringing the solution to my problem to the table… My first shot with the chronny after getting it all back together was 847 so I knew it was on its way… The last 10 shots I fired off were right in the 890 range and it seems to have settled off in that realm which I’m happy with. It is strange that I saw no O ring nor Delrin washer when I opened it up so it’s possible it came out without me seeing it I suppose…? I did adjust the hammer as well so who knows if it had just worked it’s way out as mentioned here as well and it was metal on metal prior to me installing the washer? So either way I’m happy I took it apart and it’s now shooting like it should and I know my hammer spring isn’t smashing into metal and prematurely wearing out my gun! I am going to take the advice and apply some loctite on my hammer spring adjuster as well to avoid it from slowly lessening the tension after every shot. You guys are awesome and I really appreciate the time taken to lend some help! It saved me from having to possibly send my gun out to be fixed and that’s never a fun proposition so THANK YOU!!
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